Portland-area apartment vacancy grew to 3.72% in the last year, but rents climbed 3% in the same period.

The Portland area has one of the lowest rental vacancy rates in the country. Last year, the U.S. Census Bureau and the National Association of Realtors both ranked Portland the second-tightest rental market among the largest metro areas.

That's good news for owners of apartment buildings, who can push rents higher without risking empty units.